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ARM: S3C: Add info for supporting circular DMA buffers

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The S3C64XX DMA implementation will work a lot better with the ability
to enqueue circular buffers as the hardware can do it's own linked-list
management.

Add a function s3c_dma_has_circular() to show that the system can do this
and a flag for the channel.

Update the s3c24xx/s3c64xx I2S DMA code to deal with this.

Signed-off-by: Ben Dooks <ben@simtec.co.uk>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Acked-by: Mark Brown <broonie@@opensource.wolfsonmicro.com>
This commit is contained in:
Ben Dooks 2009-09-22 16:48:56 +01:00
parent 964fe080d9
commit e3d8024891
3 changed files with 27 additions and 2 deletions
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7
arch/arm/mach-s3c2410/include/mach/dma.h
View file

@ -110,6 +110,8 @@ enum s3c2410_dma_loadst {
* waiting for reloads */
#define S3C2410_DMAF_AUTOSTART (1<<1) /* auto-start if buffer queued */
#define S3C2410_DMAF_CIRCULAR (1 << 2) /* no circular dma support */
/* dma buffer */
struct s3c2410_dma_buf;
@ -194,4 +196,9 @@ struct s3c2410_dma_chan {
typedef unsigned long dma_device_t;
static inline bool s3c_dma_has_circular(void)
{
return false;
}
#endif /* __ASM_ARCH_DMA_H */

5
arch/arm/mach-s3c6400/include/mach/dma.h
View file

@ -68,6 +68,11 @@ static __inline__ int s3c_dma_has_circular(void)
#define S3C2410_DMAF_CIRCULAR (1 << 0)
static inline bool s3c_dma_has_circular(void)
{
return false;
}
#include <plat/dma.h>
#endif /* __ASM_ARCH_IRQ_H */

17
sound/soc/s3c24xx/s3c24xx-pcm.c
View file

@ -75,11 +75,19 @@ static void s3c24xx_pcm_enqueue(struct snd_pcm_substream *substream)
{
struct s3c24xx_runtime_data *prtd = substream->runtime->private_data;
dma_addr_t pos = prtd->dma_pos;
unsigned int limit;
int ret;
pr_debug("Entered %s\n", __func__);
while (prtd->dma_loaded < prtd->dma_limit) {
if (s3c_dma_has_circular()) {
limit = (prtd->dma_end - prtd->dma_start) / prtd->dma_period;
} else
limit = prtd->dma_limit;
pr_debug("%s: loaded %d, limit %d\n", __func__, prtd->dma_loaded, limit);
while (prtd->dma_loaded < limit) {
unsigned long len = prtd->dma_period;
pr_debug("dma_loaded: %d\n", prtd->dma_loaded);
@ -123,7 +131,7 @@ static void s3c24xx_audio_buffdone(struct s3c2410_dma_chan *channel,
snd_pcm_period_elapsed(substream);
spin_lock(&prtd->lock);
if (prtd->state & ST_RUNNING) {
if (prtd->state & ST_RUNNING && !s3c_dma_has_circular()) {
prtd->dma_loaded--;
s3c24xx_pcm_enqueue(substream);
}
@ -164,6 +172,11 @@ static int s3c24xx_pcm_hw_params(struct snd_pcm_substream *substream,
printk(KERN_ERR "failed to get dma channel\n");
return ret;
}
/* use the circular buffering if we have it available. */
if (s3c_dma_has_circular())
s3c2410_dma_setflags(prtd->params->channel,
S3C2410_DMAF_CIRCULAR);
}
s3c2410_dma_set_buffdone_fn(prtd->params->channel,